Manufacture of rubber material



Feb. 11, 1941.l Efo. DIETERICH MANUFACTURE OF RUBBER MATERIAL FiledJuly 2f?, 1958 Patented Feb. 11, 1941 UNITED STAT-Es PTET FFIC'E Akron, Ohio, assigner to The B. F. Goodrich Company, New York, N. Y., a corporation of New York Application July 27,1938, `Serial No. 221,5 85

4 Claims.

This invention relatesto themanufacture of rubber material `and. isV Vespecially useful 4where longlengths of soft sheet rubber are to be manufactored.

5 In the manufacture of thin sheetv rubber of high quality such as the material used for lproducing rubber thread for use in the .manufacture of elastic garments and the `windings of` golf balls, it is desirableto produce the sheet material in pieces of great length. The` material must also have uniform physical properties throughout. It is therefore necessary that vulcanization be uniform.. J

` ,Ithasbeen thepracticeto `windthecalendered 15, sheet, after it has cooled from .the calendering operation,upon a hollow drumpf relatively large .diameter between layers of .liner clothand tosub.-

ject the material to vulcanization by placing the drum in a vulcanizing chamber, lusually `filled with hot water or steamunderpressure. In order to provide as uniform a vulcanizationV as possible the total thickness Yof the material wound upon the drum must be relatively small as otherwise the innermost andv outermost convolutions, being almost directly incontact with the heating fluid, will become fully vulcanized in advance of the intervening convolutions. It hask also been necessary in the past to subject the material to agradually .increased `temperature `over u a long l period 3Q of time starting with a temperature well below the 'temperature of vulcanization in anl effort to equalize vulcanization of the convolutions by bringing themV up to vulcanizing temperature gradually. This has unduly lengthened the time required for vulcanization and the uniformity of vulcanization through the roll has not always been satisfactory. As the size of the drums `is limited by the dimensions of the available vul# canizing equipment and by convenience of han- 40 dling, the length of material which may be produced is limited.

The principal objects of this invention `are to provide improved procedure for the production of vulcanized rubber of great length, lto provide a high degree of uniformity of vulcanization, to

provide economy of heat, and generally tofacilitate the production of rubber sheet material.

Other objects will .appear from the following description Aand the accompanyrlfr drawing.

,50 `Of the drawing:

Fig. 1 is a. diagrammatic view in relevation of apparatus which may be used in carrying out the invention in its'preferred form.

Fig. 2 is a detail .view thereof in cross section taken online 2-2 of Fig. 1.

Fig. 3 isa similar cross sectional View taken online 3,34of Fig. 1.

Referring to the drawing, which illustrates one form of apparatus by which the invention may be practiced, the numeral lll designates a three 5 roll calender such as is used for calendering sheet rubber and Vhaving a top roll Il, a middle roll l2, and `a bottom roll i3. Abank lil of suitable rubber composition is fed between the top `roll and the middle roll Whereunder the iniiuence oi heat 10 and pressure it is rolled `into sheet form. The sheet i5 adheres to and follows them/iddle roll, where itis cut` to width by knives i6 spring pressedagainst the roll. The exposed f ace of the rubber sheet is dusted with starch or other l5 dusting material as it passes around'the middle roll, and for this purpose a brush Il is mounted tobear against Vthe sheet as it passes the middle roll `anda bank of dust i8 iskept at the entrance angle of the brush with the roll. The sheet passes 20 around the lower roll andas it is no 'longeradhesive on its roll contacting face due to the dusting of starch, a cloth faced presser roll t9 is kept in engagement with the sheet Aby a' weightv Z to cause the sheet to follow the roll. As the sheet Q25 passes the lower roll, its exposed face ,is dusted by a second dust brush 2l and a bank 22 of dust.

As the sheet leaves the calender it is passed over an inspection table where it may be inspected for flaws, such as pin holes, dirt and the .30 like. For this purpose a glass topped table 23 is employed. A bank of electric lights 2t is mounted under the glass top so that the inspector may observe the sheet by `light transmitted therethrough. lRolls 2t, 2li,` at the ,ends of the table `135 may be driven from the calender by convenient gearing to advancethe sheet.`

After the sheet has been inspected it is carried about a heated drum which is maintained at substantially the vulcanizing temperature. The `4() drum is rotatably supported upon hollow trunnlons 23, 29 supported by pedestal bearings 30, 3l. The drum is hollow and is supplied with hot Water `or other heating fluid by means oi inlet and outlet pipes-32, 33 which enterthe trunnions through 45 stufling boxes 3ft, 35. The drum may be partially surrounded by and driven by a belt 3S trained over guide pulleys 3l, 33, 39 and dit which maybe driven from any suitable source `of power. As the belt contacts with a long arc of the drum, the ,5,0 rubber material between the drum and the belt is heated substantially to vulcanizing temperature during its travel about the drum.

As considerable shrinkage takes placein the rubber sheet between the calender and the drum, 55

it is advisable to provide for driving the drum at a slower surface speed and to provide for regulating such speed. For this purpose a Reeves or other variable speed changer 4| may be provided between the belt driving pulleys and the source of power. For instance the pulleys 3l, 38, 39 and 40 may be driven by chains and sprockets from the Reeves drive 4l and the Reeves drive may be driven from the calender by a chain 42 or from an independent motor.

After the sheet material has been heated to substantially the vulcanizing temperaturait is immediately wound upon a Acuring drum in successive convolutions. The curing drum hasv been heated to vulcanizing temperature so (that no loss of heat takes place in the sheet material. For this purpose, a heating and winding drum 4l is provided. This drum is supported from one side by a hollow trunnion 42 which is rotatably mounted in a pedestal 43. The drum is hollow and is formed with a shoulder 44 on its outer face to align the curing drum which is slidably mounted upon the drum lll. The curing drum is preferably formed of a pair of rings 45, 46 rto which a shell 4l of sheet metal is attached.

Steam, hot Water, or other heating fluid is supplied to the drum by pipes t8, 49 connected to a mill-T 50 swiveled in the trunnion 42, or the drum may be heated electrically or by other `means if desired. The drum 4l may be driven through a sprocket 5l, attached thereto, from any convenient source of power, such as a motor` 52 preferably of the variable speed type, so that'it may be rotated independently of the other mechanism. The pedestal 43 which supports the drum 4I, also supports a roll 53 of fabric liner material in close proximity thereto and a pressing roll 54 journaled o-n a swing arm 55 pivotallymounted on the pedestal al, bears against the face of the drum to roll the material in place.

In practicing the method of the invention, the curing form is placed upon the heated drum 4l. Several layers of liner material'are drawn from the roll 53 and Wound upon the shell to provide a smooth pervious surface. The rubber sheet material which has been heated substantially to vulcanizing temperature by passing it around the heated drum 21, is now wound upon the curing form in successive convolutions, the starched surface preventing adhesion of the convolutions. After a sufficient length of rubber material has been wound upon the form, a plurality of layers of fabric liner are wound thereon from the supply 53. A helical Wrapping of tape is applied thereover to hold the material in place.- The curing form, and the material thereon are all at substantially the vulcanizing temperture and may be transferred to a vulcanizer where vulcanization may be started at once at the vulcanizing temperature without gradually bringing up the temperature, thereby making for greater uniformity of vulcanization throughout the rubber and considerably shortening the time of cure and simplifying the operation of Vulcanization so as not to require such constant attention of the operator as would be required for frequent adjustments of temperature.

Due to the fact that the curing form and the rubbermaterial are at the vulcanizing temperature at the start of the vulcanizing step, a relatively thicker mass of rubber, and therefore a longer continuous length thereof may be applied to the form and cured during a single operation with a high degree of uniformity of vulcanization, as the process of vulcanization, where such small percentages of vulcanizing agents are present as, for example, are used in the production of rubber thread material, is neither strongly endotherrnic or exothermic and once the mass is at the vulcanizing temperature, vuloanization proceeds uniformly therethrough as long as such temperature is 'maintainedz heat actually expended in the vulcanizing step is merely that necessary to prevent cooling ofthe mass.

If desired the steps of calendering and inspecting maybe separately performed, the process being confined to progressively heating the sheetrto substantially Vulcanizing temperature, winding it upon a curing form While maintaining `its temperature and vulcanizing the The apparatus illustrated and vdescribed here-v in is illustrative. Various changes may be made without departing from the scope of the invention as it is defined by the following claims. What is claimed is: i 1. The method of making vulcanized rubber material of a uniformly elastic nature which comprises progressively heating a single ply of unvulcanized rubber composition to substantially the vulcanizing temperature thereof, assembling the .sheet material on itself to -form a thick body comprising a multiplicity of plies thereof at substantially the vulcanizing -temperature before its temperature vhas substantially decreased in any part thereof by loss of heat, and applying further heat and pressure to the body to vulcanze the sheet material substantially uniformly throughout its extent Without substantially raising the temperature of the body beyond the temperature of the plies when assembled.

2. `The method of making vulcanized rubber vmaterial of a 'uniformly' elastic nature `which comprises progressivelyvheating a single ply of i'unvulcanized rubber composition to substantially the vulcanizing temperature thereof, Winding the sheetmaterial on itself to form a thick body comprising a multiplicity of plies thereof at substantially the, vulcanizing temperature before its temperature has substantially decreased in any part thereof by loss of heat, and applying further heat and pressure to the body` to vulcanize the sheet material substantially uniformly throughout its extent without substantially raising the temperature of the body beyond the temperature ofthe plies When assembled.

3. The method of making vulcanizedrubber material of a uniformly elastic'nature which i comprises progressively forming a single ply of unvulcanized sheet material from a mass thereofl by the use of pressure and heat sufiicient to raise the temperature of the sheet to substantially the Vulcanizing temperature thereof, assembling the sheet material on itself to,form

ia thick body comprising a multiplicity of plies to the body to 'vulcaniz the sheet material substantially uniformly throughout its extent with- Ibut substantially raising the temperature of the body beyond the temperaturel of the plies when assembled.

4, The method of making vulcanized rubber material of a uniformly elastic nature which comprises progressively forming a single ply of unvulcanized. sheet material from a mass thereof by the use of pressure and heat sufcient to raise the temperature of the sheet to substantially the Vulcanizng temperature thereof, winding the sheet material on itself to form a thick body comprising a multiplicity of plies thereof at substantially the vulcanizing temperature (before its temperature has substantially decreased in any part thereof by loss of heat, and applying further heat and pressure to the bodir to vulcanize the sheet material substantially uniformly throughout its extent without substantially raising the temperature of the body beyond the temperature of the plies when assembled.

KATHRYN J. DEIETERICH, Eecutrz'a: of the Estate of Ernest O. Dieterich,

lDeceased. 

